This relates to semiconductor fabrication including etching of substrates such as wafers.
Fabrication of integrated circuits (IC) in the semiconductor industry typically employs plasma processing to create and assist surface chemistry necessary to remove material from and deposit material to a substrate within a plasma processing chamber. Examples of plasma processing apparatus include a plasma CVD (Chemical Vapor Deposition) apparatus configured to deposit a thin film on a substrate, and a plasma etching apparatus configured to remove material from a substrate, which can include using an etch mask to define locations for removing material. In general, such plasma processing apparatus form plasma under vacuum conditions by flowing a process gas into a processing chamber and heating electrons to energies sufficient to sustain ionizing collisions. Moreover, the heated electrons can have energy sufficient to sustain dissociative collisions and, therefore, a specific set of gases under predetermined conditions (e.g., chamber pressure, gas flow rate, etc.) are chosen to produce a population of charged species and/or chemically reactive species suitable to a particular process being performed within the chamber (e.g., etching processes where materials are removed from the substrate or deposition processes where materials are added to the substrate).